Antibiotic resistance is an ever-growing clinical problem. Four years ago, a study found that antibiotics are overprescribed for sinus infections. Compounding the issue is the fact that as bacteria are learning to tolerate and even circumvent existing classes of antibiotics, not enough work is being done to discover new ones. Combinations or cocktails of antibiotics are often used to broaden the antimicrobial spectrum of each and to achieve synergistic effects; this approach has successfully been applied to combat tuberculosis, leprosy, malaria, and famously, HIV. Yet the discovery of effective combinations has usually been almost fortuitous, most often resulting from trial and error rather than a systematic analysis.

In the current study, researchers systematically examined combinations of 1,057 compounds previously approved as drugs to find those that exhibited synergy with the antibiotic minocycline. Their work is reported in the April 24, 2011 issue of the journal Nature Chemical Biology [1]. The compounds were chosen because they have already been approved as drugs, they are known to have activity in vivo and are known to be relatively safe. Many approved drugs are known to have utility for clinical indications other than those for which they initially received approval. Moreover, using pre-approved compounds also reduces the time and cost associated with developing new compounds for therapeutic use.